Bolts are best specified by outside diameter of thread x thread pitch. Thread pitch for metric bolts is how many mm between threads.
So M6x1.25 is 6mm outer diameter with 1.25mm between the threads.
Thread pitch is possible to measure by counting the threads in say, 25mm of bolt then dividing 25mm/number of threads. Or you can get a thread gauge which you mesh with the threads, like this

Like the others say, Alu bolts in your stem aren't a good idea other than possibly your top cap. Ti is miles better but watch out for corrosion - Alu and Ti galvanicaly corrode really badly together

Bolts are best specified by outside diameter of thread x thread pitch. Thread pitch for metric bolts is how many mm between threads.

I thought it was the depth of the threa rather than the distance between. So for internal threads you can measure the internal hole (including the thread) and then take an educated guess, so if your hole is metric and 8.75mm wide, its going to be an M10x1.25 thread. Useful if you can get a verier caliper or a hole guage in, but not a thread guage. Just measure it accurately.

Who is online

You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum